Sugarcane is grown on approximately 3.8 million hectares of
land which represents only 0.76 percent of Brazil's arable land
consisting of about 500 million hectares. The land actually used is
only 5.9 percent of these values. From this area, 125 million tons of
cane were harvested in the 1985/86 season. Sugar and alcohol
production were respectively 7.8 million tons and 11.9 billion litres.
Of the total sugar production only 1.8 million tons are sold outside
the country.

Sugarcane cultivation represents the third working force of
the country with 1 700 000 employees. Since 1979 alcohol production
has represented an investment of Brazilian capital equivalent to
US$ 6 billion and has represented an economy of US$ 9 billion.

The harvesting plan for 1986/87 has established a production
target of 8.5 million tons of sugar and about 11.7 billion litres of
alcohol. Alcohol production is dependent upon political decisions.
Two factors have disturbed alcohol producers: the return of oil prices
to the level of 1973 and a long, dry season that reduced production
and influenced this year's yield. Some views were that it was
necessary to stop the National Alcohol Programme. However, on
27 February, during a visit of the President of Brazil to Ribeirao
Preto, State of Sao Paulo, it was confirmed that the Programme would
continue. It is commonly agreed that some changes should be made but
the reduction in yield will give them time to decide.

2. Sugarcane by-products

The 125 million tons sugarcane harvest in the 85/86 season
gave 17 million tons of tops, 31 million tons of bagasse, 5 million
tons of filter cake, about 5 million tons of molasses, 75 billion tons
of stillage and 140 thousand tons of dried yeast.

Sugarcane tops are, in almost their totality, left in the
field. In special situations they are used for feeding animals.

Fifty percent of the bagasse produced is burned for steam
production. Some is burned for the production of electricity. From
the remaining bagasse, about 100 thousand tons are used in the paper
industry and about 140 thousand tons in furfural production which has
a very large industrial application. Small amounts are used as a crop
mulch and for animal feeding. In 1985 the southeast area had an
unusual drought during the months of October to December, so emergency
feeding for the animals on pastures consisted in low quality roughages
(including bagasse) with the addition of urea plus oil cake proteins
to cover the lack of green forages.

Filter cake has a very large variation in its chemical
composition so it is difficult to recommend it for any specific use.
Its final use is as fertilizer in sugarcane crops.

From 1979 to 1985 molasses has almost disappeared as an
animal feed being partly exported and partly transformed into alcohol.

Stillage no longer causes problems for producers and
consumers. Actually it is almost entirely used as a fertilizer, at
least as a good source of K and water, increasing the sugarcane yield
from 8 to 10 percent. After fermenting a batch of sugarcane juice,
using the Mellet-Boinot process, some yeast milk is taken off giving
about 40 g of dry matter per litre of alcohol.

3. The use of sugarcane and byproducts in animal feeding

The real amount of whole sugarcane given to domestic animals
in the country is not known but it has certainly been widely used as
green chopped forage in the majority of low production (less than 10
kg/cow/day) milking farms. A recent survey (1983) in a very
representative area of milk production, the county of Campinas, in the
State of Sao Paulo, showed that 70 percent of the farms have sugarcane
as green stock. They cover 1.3 ha in an average area of 123 ha. The
amount given, per animal, per day, on average is 14 kg (from 9.9 to
17.6). Whole sugarcane in some cases is given with cotton seed meal
or soybean meal, raising protein levels to 11–12 percent (dry basis)
which gives a daily gain of 0.7 to 0.8 kg. Lower gains have been
obtained when urea, sulphur and rice polishings are given instead of
oil cake protein.

Sugarcane tops in spite of their large availability are not
commonly used and in fact are only used in very specific situations.
One of the factors that limits their use is the collecting cost from
the field after harvesting the sugarcane. Left on the soil when
manually cut the mineral matter increases if the sugarcane tops are
not properly managed. The common practice of burning the crop reduces
production and the time available to transport them from the field
without changing their composition. Burned sugarcane tops, plus
soybean straw without pods are two kinds of residues found together in
some areas of the State of Sao Paulo. Consumption of 6.6 kg dry
matter composed of 2.6 kg of burned sugarcane tops and 4.0 kg of
soybean straw is enough to maintain the liveweight of 350 kg steers
during the dry season.

Raw bagasse has been introduced in many situations as
emergency feed. Diets including 30 percent of raw bagasse
(± 50 percent dry matter) given to Nelore cattle and buffaloes were
consumed in growing amounts in relation to time. Treatments with
ammonia, sodium hydroxide and steam cooking have actually been tested
in several places with variable results. Of these treatments, steam
cooking seems to be the one that has a more promising application in
the future. Currently more than 5 000 head of cattle are fed with one
type of steam treatment representing about 50 percent of the daily dry
matter consumption. There are still several questions to be answered
before the release of the technique. Some of the equipment used for
steam treatment does not have good control of temperature and time, so
it is very difficult to know what are the real working conditions. It
is well known that small variations in these parameters can change
considerably the digestibility and probably the consumption of the
steam treated bagasse.

Molasses was largely used before 1975 and it seems that, if
no big changes occur in the oil price, it will again be available for
animal feeding.

Dried yeast tested as a protein source for ruminants, totally
substituted cotton seed and soybean meal for beef and dairy cattle.
Consumption of up to 4 kg/animal/day was not detrimental to the
animals. The possibility to take off 40 percent of dried yeast,
without affecting alcohol production, opened a new set of
opportunities for the utilization of this source of protein. The
strategy towards yeast production in relation to alcohol will be
decided by international prices and Brazilian internal policy. The
“Usina Santa Luiza”, one of the alcohol producers in the State of Sao
Paulo, has a daily production of 4 tons of dried yeast, which, over
the entire sugarcane harvesting season, gives about 800 tons (1983).
The producers mentioned export of 250 tons to UK in 1983 and about
1 000 tons in 1984.

Stillage as it comes after distillation (2 to 7 percent of
dry matter) has also been used as a palatability agent for low quality
forages. Corn husks and cobs 50 percent (W/W) and stillage 50 percent
(W/W) had a 10 percent increase in nutritive value compared to the
first one alone. Stillage has been used in mixtures with low quality
forages and ensiled. Some mixtures balanced in nutrients can
constitute a complete ration.

Concentrated syrup (± 48 percent of dry matter, pH = 4.5)
has a detrimental effect on the animals when representing more than 7
percent of the total diet dry matter.

Two research projects dealing with sugarcane are presently in
operation. One is the use of steam exploded bagasse in rations for
beef and dairy cattle. The other is the establishment of an
integrated system of sugarcane utilization, starting with direct
fermentation in the plant without tops, distillation of the biomass
and the residue given as a partial ration to the animals in the
feedlot, faeces and urine producing biogas, biogas used to produce
heat for distillation (or for any other kind of use) and the final
residue returned to the field as fertilizer.

The use of steam exploded bagasse at temperatures of
200–210°C, pressure toward 18 kg/cm2 for 5 minutes has given promising
results in terms of nutritive value measured in the laboratory and in
short feeding trials with sheep and steers. Small feedlots receiving
diets with 50 percent dry matter from steam treated bagasse for more
than 100 days, have shown a constant drop in dry matter intake in
relation to time. It was suspected that the furfural produced in the
process was partially retained in the mass. Levels, in terms of free
furfural in the filtrate, varied from 0.14 to 0.35 percent, the
potential value varied from 0.42 to 0.66 percent and the potential
furfural level in the solids varied from 0.37 to 7.59 percent. The
representativeness of these figures is not yet known, but what is
surprising is the large variability of the potential furfural in the
solid, despite physical conditions being the same. This year it is
planned to go deeper into the analyses of chemical residues produced
during the process. Analyses of the fibre portion that represents
91.6 percent in the dry matter expressed as Neutral Detergent Fibre in
the raw bagasse, drops to 67.2 percent in steamed bagasse.

Hemicellulose in the first case is 29.1 percent and in the
second only 10 percent. Steamed bagasse mixed with corn ground grain,
urea, ammonium sulphate and several other ingredients, in such a way
to give more or less 30 percent of dry matter was ensiled in small
plastic silos. “In vitro” dry matter digestibility and “in situ”
nylon bag technique gave higher figures when compared to non-fermented
steamed bagasse. This year testing will be done with animals.

The integrated sugarcane system project has just begun. Some
of the initial problems in relation to the sugar level in the mass and
transportation of the material have been solved. The residue left
after distillation had an increase in the protein level from 1.25 to
6.8 percent. The nutritive value will be better evaluated this year
when routine work will be started.

4. Perspectives

At this point it is important to find out what is happening
in the country now and what kind of strategies are under way. With
this in mind a profile can be drawn of the type of residues available
in the near future. It is well known that Brazil has a huge
sugar-alcohol industry. Its survival is very dependent upon the
efficiency of utilization of the sugarcane yielded and a better use of
the residues produced. It was recently said that the new alcohol
distillery will be a chemical industry using renewable sources of
carbon. It will be based on the conversion of starchy and cellulosic
materials to single sugars which will be transformed biologically to
several chemical feedstocks now produced by petrochemistry.

The first and main factor that affects production is
sugarcane and sugar yield per unit of area. Recent varieties produced
20 percent more than the older ones. The variety SP 70–1143 produces
21.1 tons of sugar per ha against 17.4 of the NA 56–79. The extension
of the harvesting season and the payment for the amount of sugar in
the harvested sugarcane are two new strategies that will increase
productivity and total production.

At the industrial level new technologies have been applied
and many others are under way in different sugar mills or
distilleries. The Bagatex Industry installed in the “Usina Santa
Lydia” in Ribeirao Preto - Sao Paulo, developed a project to reduce
bagasse moisture from 50 to 20 percent and actually more than 20 new
installations will be working this year. The stillage production with
new techniques can be reduced from 13–16 1/per litre of alcohol to
3–4 1. Recycling stillage is now largely used. Centrifuged stillage
gives a product very similar to the yeast produced in the fermentation
bath.

Many other new developments have been tested on a small
scale, such as: a) the use of a bacteria Zymomonas mobilis instead of
Saccharomyces; b) use of immobilized enzymes; c) extraction of K,
lactic and succinic acid and glycerine from stillage; d) reduction of
water in distilled alcohol with absorption agents like Silicalitas
ZSM-5 and ZSM-11; e) extraction of hemicellulose by-products
specially D-Xylose and f) saccharification of cellulose with the
yeast Pachysolen tannophilus.

One question that can be raised is, if these technologies
will change the relation in many cases of product to byproduct or
residue? What will remain for animal feeding will be the result of
the new technologies applied. We can guess that whole sugarcane will
still be largely used with the addition of some source of nitrogen.
Sugarcane tops, if available, will only be used in very specific
situations. The situation of molasses, a strategic byproduct, will be
uncertain. Low moisture stillage (free of K), or centrifuged
stillage, probably would substitute molasses and probably there will
be plenty of yeast produced in different ways.